Lavoisiera adamantium Barreto ex Pedersoli (1979

Martins, Angela B. & Almeda, Frank, 2017, A Monograph of the Brazilian endemic genus Lavoisiera (Melastomataceae: Microlicieae), Phytotaxa 315 (1), pp. 448-450 : 448-450

1. Lavoisiera adamantium Barreto ex Pedersoli (1979 /1980: 21–22). Type:— BRAZIL. Minas Gerais: “Açude próximo a Diamantina ,” 11 November 1937, H. L. Mello Barreto 9737 (holotype: BHCB ex BHMH!; isotypes: BHCB-000214-n.v., online image!, CEJS-31940, ESA-66056-n.v., online image!, HEPH-16207, SP-343226, SPF-143231). In the protologue, Pedersoli designates the type of this species as follows: “Typus: Brasil. Minas Gerais: Açude próximo a Diamantina , 11 de novembro 1937- Mello Barreto-9.373 HOLOTYPUS: BHMH-22.136.” There appears to be no specimen with this collection number at BHCB, BHMH, or elsewhere. We suspect that the number used by Pedersoli for Mello Barreto’s type collection (9373) is a typographical error. The holotype, which we have examined, was collected on 11 November 1937 near Diamantina and has the collector and number as Mello Barreto 9737 (BHMH-22.136) on the specimen label. The specimen photo included in the protologue is also an exact match for the holotype. All isotypes examined online also agree with this corrected collection number.

Erect, dichotomously branched subshrub s 0.5–1.5 m tall. Branches and branchlets rounded, furrowed longitudinally on opposite faces, glabrous, frequently defoliating at the base; internodes 3–4 mm long, corky, with knobby thickenings that persist where a leaf has fallen away, nodes with inconspicuous glandular trichomes. Leaves sessile, semi-amplexicaul, densely imbricate and concealing the internodes at the ends of branchlets, sometimes spreading basally; blade 6–9 × 4–6 mm, coriaceous, rigid, slightly keeled, ovate to ovate-oblong, base rounded to subcordate, apex obtuse to subacute and shortly mucronulate, margin entire, eciliate, with an inconspicuous callose thickening, glabrous on both surfaces or sparsely beset with small sessile glandular trichomes, pale green to dark green (when dry), occasionally reddish at the base and margins, 1-nerved. Flowers (7–)8-merous, solitary, terminal (but becoming central or pseudolateral with elongation of lateral branches), sessile. Bracts subtending the flowers sometimes increasing in size and width upward on the inflorescence but similar to the principal leaves and frequently undifferentiated. Hypanthium (at anthesis) 5–6 × 6 mm, broadly campanulate, 7–9 mm wide at the apex, green, basal half red, the distal half and calyx lobes brown on maturing fruit, glabrous. Calyx tube up to 1 mm long; calyx lobes (at anthesis) 3–3.5 × 2–2.5 mm, subrounded to triangular-ovate with acute, apical tooth, the lobes persistent to tardily caducous in post-anthesis, glabrous on abaxial surface, sparsely beset with sessile glandular trichomes at the base of adaxial surface, reddish. Petals 10–15 × 8–11 mm, pink or bright pink, obovate, apex asymmetrically rounded to truncate, base attenuate to long unguiculate, margin entire or minutely glandular-ciliolate. Stamens 14 or 16, dimorphic: large (antesepalous) stamens (7–)8, filaments 6–8 mm long, anther thecae 3–4 × 1 mm, dark red, oblong, rostrum ca. 1 mm long, yellow, pedoconnective 6–7 mm long, appendage 1.5–2 mm long, oblong and bilobulate at the apex, yellow; small (antepetalous) stamens (7–)8, filaments 4–5 mm long, anther thecae 3–4 × 1 mm, yellow-orange, oblong, rostrum ca. 1 mm long, pedoconnective 1–1.5 mm long, appendage 0.5 mm long, inconspicuous, truncate to rounded, yellow. Ovary 6(–7)- locular, 1/3 inferior, style 6–9 mm long, curved and slightly enlarged at the apex, glabrous, stigma ± truncate to punctiform. Fruiting hypanthium (including calyx lobes) 7–8 × 6 mm, oblong. Capsule (at maturity) 4–7 mm long, globose, enveloped by the persistent hypanthium and calyx lobes, dehiscing from the base to the apex, brown. Seeds 0.71–1.15 × 0.48–0.51 mm, oblong to subreniform to somewhat L-shaped, light yellow brown to dark brown, periclinal cell walls of the testa convex and low domed (colliculate) when young becoming faintly concave (foveolate), the raphal zone about 30–35% the length of the seed. Chromosome number unknown.

Illustration:— Figure 15 .

Photographic image:— Figure 1A .

LAVOISIERA ( MELASTOMATACEAE )

Phytotaxa 315 (1) © 2017 Magnolia Press • 41 42 • Phytotaxa 315 (1) © 2017 Magnolia Press

MARTINS & ALMEDA LAVOISIERA ( MELASTOMATACEAE )

Phytotaxa 315 (1) © 2017 Magnolia Press • 43

Phenology:—Flowering May, October through December; fruiting October and April (old).

Distribution and habitat: —Endemic to the Diamantina plateau of the Cadeia do Espinhaço in Minas Gerais at 1000–1416 m elev. It is local to uncommon in campo rupestre, campo limpo, campo arenoso, river margins, grassy fields and seepage slopes. In the município of Serro it has been found growing with L. bradeana , L. chamaepitys , L. imbricata , L. mucorifera , and L. rigida . On the road to Conselheiro Mata it grows with L. humilis and L. crassifolia . Figure 16 .

Conservation status:— This species is known from fewer than 15 collections. At least one population is afforded some protection in Parque Estadual do Biribiri. The EOO is 12 km ² and the AOO is also 12 km ². Humaninduced fires remain the principal threat to the habitats in which it grows. Based on this threat coupled with its limited area of distribution we recommend a classification of Critically Endangered (CR): B1ab(iii).

Discussion:— Lavoisiera adamantium is a rigid shrub with open dichotomous branching, small (6–9 mm) ovate to ovate-oblong coriaceous leaf blades that are held perpendicular to the branches but appear densely imbricate when dry. The leaf blades are 1-nerved and glabrous on both surfaces or sparsely beset with small sessile glandular trichomes. Its flowers are solitary and prevailingly 8-merous (rarely 7-merous), the hypanthia are glabrous, the petals are pink, the larger set of anther thecae are bright red with a yellow rostrum, and the ovary is typically 6-locular (rarely 7-locular). The floral merosity, ovary locule number, and combination of corolla and large anther colors are unmistakable and not readily confused with other species. The only other species with modally 8-merous flowers and a 6-locular ovary is L. sampaioana but it differs by its principal leaf blades that are coarsely pectinate and callose-thickened with gland-tipped trichomes and hypanthia that are densely covered with spreading gland-tipped trichomes.

In habit, only Lavoisiera crassifolia and L. rigida approach L. adamantium . The former has 5–6-merous flowers (rarely 7-merous) and a 5–6-locular ovary and the latter has 6–7 flowers (rarely 8-merous) and an 8-locular ovary. Both of these species also differ consistently in having large anther thecae that are mostly yellow or orange-pink but never intense red with a yellow rostrum.

Additional specimens examined:— MINAS GERAIS: Mpio. Diamantina , 4 km W of Hwy No. MG 220 along the road to Conselheiro Mata , 18°16'S, 43°42'W, Almeda et al. 8504 (CAS!, MO!, NY!, UEC!, US!); Mpio. Diamantina , 13 km south of the main plaza in Diamantina on the road to São Gonçalo do Rio das Pedras, 18˚18.884’S, 43˚33.072’W, Almeda et al. 9102 (CAS!, COL!, MO!, UEC!); Mpio. Diamantina , 4 km W of Hwy MG 220 along S side of road to Conselheiro Mata , 18°.27630’S, 43°.71281’W, Almeda et al. 9605 (BHCB!, CAS!, NY!, RB!, UEC!); Mpio. Diamantina, Parque Estadual do Biribiri, “São Miguel”, 18°11.347”S, 43°35.950”W, Araújo et al. 198 (HUFU!, UEC!); Mpio. Diamantina, Duarte 14030 (M!, US!); Mpio. Diamantina , estrada Diamantina-Biribiri, a 9 km de Diamantina, Giulietti et al. CFCR 2540 (SPF!, UEC!, US!); Mpio. Diamantina, Tombador , perto de Diamantina, Glaziou 19247 (BR!, C!, LE!, P!, R!); Entre Biribiri e Diamantina, Glaziou 19248 (BM!, BR-2!, C!, F-2!, K!, LE!, NY!, P!); Mpio. Diamantina, Biribiri, Hatschbach & Pelanda 28017 (C!, MBM!, US!); Mpio. Diamantina, Pururuca, Mello Barreto 22143 (BHCB ex BHMH!); Mpio. Serro, Capivari, Mendes Magalhães 1647 (BHCB, BHCB ex BHMH!); Mpio. Diamantina, Biribiri, Schwacke 7811 (BHCB!); Mpio. Diamantina , estrada Diamantina a Corinto até 10 km, Shepherd et al. 3865 (MBM!, NY!, UEC!, US!).

Figures

FIGURE 1. Images of Lavoisiera species. A. L. adamantium (Almeda et al. 8504). B–C. L. alba (Almeda et al. 9624). D–E. L. arachnoidea (unvouchered image). F. L. belinelloi (Almeda et al. 8532). G. L. bradeana (Almeda et al. 9718). H. L. canastrensis (Almeda et al. 7878). I. L. caryophyllea (Almeda et al. 9172). J–K. L. chamaepitys (Almeda et al. 8500). L. L. confertiflora (Almeda et al. 9725). Image credits: A–C, F–L. Frank Almeda; D–E. Karina Fidanza.

FIGURE 15. Lavoisiera adamantium. A. Habit. B. Abaxial leaf surface. C. Adaxial bract surface. D. Flower. E. Hypanthium, calyx lobes and style with enlarged detail of adaxial calyx lobe apex (upper left) and detail of adaxial intercalycine sinus (upper right). F. Ovary cross-section. G. Petal with margin detail (right). H. Ventral view of antesepalous stamen. I. Ventral view of antepetalous stamen. J. Seed. (Based on: A–I, Araújo et al. 198, HUFU, UEC; J, Almeda et al. 8504, CAS, UEC.)

FIGURE 16. Distributions of Lavoisiera adamantium, L. firmula, L. humilis, L. pulcherrima, and L. subulata.